Single versus double field rate: Do different rates of fenoxycarb in chronic Oomen bee brood feeding tests cause different effects sizes?

Background: EFSA (2013) recommends to modify the Oomen bee brood feeding test (Oomen et al., 19922) from an acute to a chronic feeding test, but proposals regarding the concentration of the reference item fenoxycarb in such trials are missing. For the chronic Oomen bee brood feeding ring-test (see Lückmann & Schmitzer 2014) the double field rate was used. Due to the lack of information about the effect size of the single field rate two separate bee brood feeding tests (following the method given by the ring-test protocol) were conducted: one in July 2013 (study 1) and one in April 2014 (study 2). The single and the double field rate of fenoxycarb were applied each at both times. As endpoints effects on brood termination rate (BTR) of marked eggs, young and old larvae, pupal mortality and colony development (i.e. number of brood cells and colony strength) were recorded and evaluated.Results: The chronic administration of the double field rate caused reproducible results whereas those of the single field rate were more variable. Distinct (i.e. ≥ 50%) and statistically significant increased BTRs of eggs were observed for the single rate in study 2 only, and for the double rate in both studies. Pupal mortality was statistically significantly increased at both rates in both studies and also bee brood and colony strength development was affected at both rates in both studies. Distinct dose-related differences between the two test rates were present for the BTRs of eggs in study 1 and for pupal mortality and colony development in study 2.Conclusion: The chronic feeding of the single rate of fenoxycarb did not cause reproducible, doserelated effects. Therefore it is recommend using the double field rate of fenoxycarb as the toxic reference item dose in chronic Oomen bee brood feeding studies as long as no further data are available on the effect size of the single rate.Keywords: honeybees, chronic Oomen bee brood feeding test, fenoxycarb, single rate, double rat

Daily life stress and the cortisol awakening response : testing the anticipation hypothesis

Acknowledgments We thank Paul Stewart for his contribution to data collection and Dr Matthew Jones for programming the handheld computers. Author Contributions Conceived and designed the experiments: WS DJP. Performed the experiments: DJP. Analyzed the data: WS. Wrote the paper: WS DJP.Peer reviewedPublisher PD

Delay and reward choice in ADHD: an experimental test of the role of delay aversion

Children with attention deficit/hyperactivity disorder (ADHD) choose smaller sooner (SS) over larger later (LL) rewards more than controls. Here we assess the contributions of impulsive drive for immediate rewards (IDIR) and delay aversion (DAv) to this pattern. We also explore the characteristics of, and the degree of familiality in, ADHD SS responders. We had 360 ADHD probands; 349 siblings and 112 controls (aged between 6 to 17 years) chose between SS (1 point after 2 s) and LL reward (2 points after 30 s) outcomes on the Maudsley Index of Delay Aversion (Kuntsi, Oosterlaan, & Stevenson, 2001): Under one condition SS choice led to less overall trial delay under another it did not. ADHD participants chose SS more than controls under both conditions. This effect was larger when SS choice reduced trial delay. ADHD SS responders were younger, had lower IQ, more conduct disorder and had siblings who were more likely to be SS responders themselves. The results support a dual component model in which both IDIR and DAv contribute to SS choice in ADHD. SS choice may be a marker of an ADHD motivational subtype

Who is Ivan Schwab?

Background: impulsive drive for immediate reward (IDIR) and delay aversion are dissociable elements of the preference for immediate over delayed rewards seen in attention-deficit/hyperactivity disorder (ADHD). We hypothesized that IDIR would be associated with dopamine regulating genes and delay aversion would be associated with serotonin-regulating genes.Methods: impulsive drive for immediate reward and delay aversion were measured in 459 male children and adolescents (328 ADHD and 131 unaffected siblings) with a laboratory choice task. The sample was genotyped for the 5HTT (SLC6A4) promoter serotonin-transporter-linked polymorphic region polymorphism and a DAT1 (SLC6A3) 40-base pair variable number tandem repeat located in the 3?-untranslated region of the gene.Results: there was no effect of dopamine transporter (DAT)1 on IDIR. As predicted, serotonin-transporter-linked polymorphic region s-allele carriers were more delay averse. This effect was driven by the s/l genotype in the ADHD group. These results were not altered by taking account of the rs25531 A/G single nucleotide polymorphism and were independent of age, IQ, and oppositional defiant disorder symptoms.Conclusions: the results support the genetic distinctiveness of IDIR and delay aversion in ADHD and implicate serotonin function in delay aversion. Possible explanations of the heterosis effect in the ADHD cases are presente